Sometimes the prosecution (prostitution? as they would say on Married With Children) will claim "inevitable discovery." But also the defense would have to establish that the warrant was illegal, and the govt would claim that would reveal their "sources and methods."
In my opinion, they have found a way to get around the 4th amendment, and Trump can't refuse to sign reauthorizations of the Patriot Act because they get attached to appropriations bills. There are bad congresscritters in both parties.
SCOTUS might be afraid to rule against the Patriot Act.
FISA is "make work" to give the utterly false impression that the government practices restraint in snooping.
I know of ZERO cases where the government lost a prosecution for an illegal wiretap. Closest ever was al-Haramain Islamic Foundation.
The only "real" penalty for illegal wiretapping is the evidence can't be used in a criminal prosecution.
FISA is itself a way around the 4th amendment. Get a warrant, get a legal defense. See 50 USC 1809(b).
Nobody in the FBI is going to be charged for snooping. Charge FBI for using FISA for criminal snooping, and all of FISA gets thrown out because FISA is an unconstitutional encumbrance on warrantless spy vs. spy snooping.